concentrated acids MERCK, India Ltd., by using distilled and de-ionized water. The pretreated
cellulose porous solid fibers were Aldrich Chemicals used for their chemical modification.
The standard solution for the analysis of carbonate was prepared from the sodium
c ar bo n a te
M E R C K C h e m ic al s .
Th e standardization of carbonate ion was done either
by acid-base titration or ion selective electrode depending on the carbonate ion concentrations.
Carbonate ions were prepared by bubbling CO
2
in aqueous solution and then carbonate ions were
standardized by standard methods. Magnesium was determined by EDTA titration, precipitation
and flame
photometry depending
on concentration. Citric acid was estimated by acid-
base titration. 1,10 phenanthroline or 2,2’ bipyridine was determined acid-base titration or
spectrophotometry depending on concentration. The fiber supported solid membrane cell was used
to measure the permeability coefficient P Figure 1. The carbonate ion concentration was
determined with respect to time from the source and receiving solutions.
2.2 Chemically modification of cellulose Fiber
The porous solid fibers were used with dimensions, the diameter 0.027 cm 270 µm,
porosity 30 to 50 and cross section area 5.73 x 10
-4
cm
2
. The cellulose fibers were modified chemically by the scheme.
The modified cellulose fiber supported solid membrane was prepared [26-29]. The pre-treated
cellulose fibers were treated with 0.5 M citric acid in the ratio of 1:12 cellulose fiber: acid, wv
under stirring for 30 min, and then keeping in a stainless steel reactor and dried at 50
o
C in a forced air oven for 24 h. The thermo-chemical
esterification of citric acid and cellulose fiber was carried out in the oven at 120
o
C for 90 min. The esterified cellulose fibers were washed with
distilled water until the filtrate is free from citric acid Tested as no turbidity with 0.1 M lead II
nitrate solution. The combined complex of magnesium with esterified cellulose fibers and
2′2-bipyridine were formed with the treatment of magnesium
salt by
stirring. The
excess magnesium carbonate and 2′2-bipyridine were
removed by washing thoroughly with distilled water and then ethanol. The wet modified
cellulose fibers were dried at 50
o
C for 24 h, and then preserved in desiccators for further use.
2.3 Procedure
In the source phase compartment of the cellulose fiber supported solid membrane cell, a
suitable carbonate ion concentration in 15 ml was used. In the receiving phase compartment of
cellulose fiber supported solid membrane cell, 15 ml of aqueous solution containing the appropriate
concentration of sodium hydroxide was used. The source and receiving phases were connected by
fiber supported solid membrane through a teflon tube. The transport of carbonate ions through
cellulose fiber supported solid membrane was studied by varying the experimental parameters
such as cellulose fiber membrane length, carbonate ion concentration in the source phase,
stirring of bulk phases, NaOH concentration in receiving phase, etc. The transported carbonate
ions per unit membrane length, cross section area and time were estimated. In order to test the
adsorptive transport of CO
2
through cellulose fiber supported solid membrane, the permeability
of carbonate ions were determined withwithout bubbling CO
2
with a flow rate 0, 1, 2, 4, 6, 8, 10 mlmin in the source phase. The samples of the
source and receiving phases were analyzed for carbonate ions with respect to time.
3. Results and Discussion 3.1 Mechanism of transport of carbonate
